With the rapid development of display technology, touch screens have been gradually spread to various aspects of people's lives. According to the work principle, touch screens can be divided into: a resistance type, a capacitive type, an infrared type, a surface acoustic wave type, an electromagnetic type, a vibration wave sensing type, and a frustrated total internal reflection optical sensing type. The capacitive type touch screen has become a research hotspot due to its advantages such as unique touch control principle, high sensitivity, long lifespan and high light transmittance. The electromagnetic type touch screen can be widely used in many high-end computer aided drawing systems, such as AutoCAD, due to its feature of realizing the original handwriting.
At the same time, with the rapid development of portable electronic terminal devices, especially mobile phones and tablet technologies, more and more new technologies are being applied to these terminal devices. Force touch technology is a new technology which draws extensive attention in the present field, and is called “a great change after multi-touch technology.” By means of using the force touch technology, the terminal devices can not only recognize every touch of the user, but also sense the magnitude of the touch, and give different feedbacks according to the magnitude of the touch. For example, upon a user viewing a picture, a system of a mobile phone automatically enlarges the picture according to the force of the user's finger on the screen. For example, the greater the force, the greater enlargement extent of the picture.